WhatsApp Messenger is a cross-platform mobile news app that allows the free transmission of news, images, videos and voice memos between users. The app works over the user’s existing Wi-Fi or 3G/4G connection, and offers alerts via a push service. The tool is available for Android, BlackBerry, iOS, Symbian and Windows Phone.

WhatsApp is free of charge in the first year, and thereafter it requires an annual fee of $0.99. (The description in the app store by Apple does not mention the annual fee.)

WhatsApp is one of the most popular smartphone apps. The reason for this is clear: while users pay for each SMS or MMS sent, the sending of short messages on WhatsApp is free of charge. In recent months however the app has made headlines over security issues, with some saying its encoding mechanism can be easily cracked. However, WhatsApp says it has fixed these security issues with the latest version.